The present invention relates to a fluid pressure cylinder with a pressure-intensifying function. more particularly, the present invention relates to a fluid pressure cylinder wherein the fluid pressure inside the fluid pressure cylinder is pressurized to high pressure by means of a gas spring.
Conventionally, gas springs are used in a variety of mechanisms, such as shock-absorbing/damping mechanisms for press machines, mechanisms for elastic die supports used in multi-stage drawing fabrications, and the like. Gas springs, in general, have a cylinder, a gas actuating chamber within this cylinder filled with compressed nitrogen gas, and a pressure-receiving part which receives the gas pressure of this gas actuating chamber. An output rod, integral with the pressure-receiving part, extends to the exterior of the cylinder and is pushed to the protruding side by the gas pressure of above-indicated compressed nitrogen gas.
For example, where a gas spring is applied as a damping mechanism in a press machine, a damping action is obtained by having the moving parts, such as the press slides, pull out/push in the output rod in opposition to the pushing of the gas pressure of the gas spring. Filling the gas actuating chamber of the gas spring with compressed nitrogen gas is usually done using an existing gas tank. The gas pressure inside a gas tank is 10 MPaxcx9c15 MPa, and, due to the relationship that as gas is consumed the gas pressure drops, the gas pressure of the compressed gas which fills the gas actuating chamber is set at a gas pressure (for example, 7 Mpa) lower than the gas pressure within the gas tank.
With a conventional gas spring, it is difficult to fill the gas actuating chamber with high-pressure compressed nitrogen gas. As a result, to be able to generate a strong pushing force and support a large load, it is necessary to have a large gas spring. Such springs will not fit in small spaces and their production costs are high. On the other hand, if the gas pressure of the compressed nitrogen gas which fills the gas actuating chamber is made excessively high, problems occur, such as leakage of the compressed nitrogen gas to leak to the outside.
It is an object of the present invention to provide a pressure-intensifying fluid pressure cylinder which overcomes the foregoing problems.
It is another object of the present invention to pressurize, by means of a gas spring, the liquid in a liquid pressure cylinder to a pressure higher than the gas pressure in the gas actuating chamber. This enables generation of a strong pushing force, thus enabling the support of large loads.
It is a further object of the present invention to provide a fluid pressure cylinder having reduced size, reduced production cost.
It is yet another object of the present invention to provide a fluid pressure cylinder to enable a reset action by means of liquid pressure.
The fluid pressure cylinder with a pressure-intensifying function of the present invention comprises a cylinder body; a liquid chamber formed within the cylinder body, filled with liquid; an output piston which receives the liquid pressure of this liquid chamber; a gas spring having a gas actuating chamber filled with compressed gas and a pressure-receiving means which receives the gas pressure of the gas actuating chamber; wherein the gas spring can pressurize the liquid in said liquid chamber to a pressure higher than said gas pressure.
It is desirable to use oil as the above-mentioned liquid and compressed nitrogen gas as the above-mentioned compressed gas. The gas actuating chamber of the gas spring is filled with compressed gas and the pressure-receiving device receives this gas pressure. The liquid chamber is formed within the cylinder body of the liquid pressure cylinder. By means of the gas spring, the liquid contained in the liquid chamber, is pressurized, via a pressure-receiving device, to a pressure higher than the gas pressure of the gas actuating chamber. The pressurized liquid pressure is received by an output piston.
As the gas spring pressurizes the liquid in the liquid pressure cylinder to a pressure higher than the gas pressure in the gas actuating chamber, it becomes possible to generate a strong pushing force and support heavy loads. By charging the gas actuating chamber with compressed gas from an existing compressed gas supply source, such as a gas tank, the liquid pressure of the liquid chamber can be intensified by several times by means of the pushing force of the gas spring, making it possible to generate the above-mentioned strong pushing force. As a result, the structure of a fluid pressure cylinder with a spring function can be made smaller, resulting in advantages in preventing leaks of the compressed gas and lower production costs.
According to a feature of the present invention, it is desirable that the above-mentioned gas spring cylinder part be formed integrally with the above-mentioned cylinder body and the gas spring and liquid pressure cylinder be position in a straight line pattern. In this case, the fluid pressure cylinder with pressure-intensifying function can be made as a simple structure enabling a reduced production cost.
According to a feature of the present invention, inside the above-mentioned cylinder body, a partitioning means may be provided which separates the liquid chamber and gas actuating chamber. This partitioning means may be secured to the cylinder body by a threaded fit. In this case, in a cylinder body formed integrally with the cylinder part, it is easy to form a liquid chamber and a gas actuating chamber.
In addition, a passage hole maybe formed in above-mentioned partitioning means into which the output rod of the pressure-receiving means is slidably inserted. In this case, the end of the output rod can be made to contact the liquid in the liquid chamber and surely pressurize that liquid.
In addition, to retract the pressure-receiving means, a xe2x80x9cliquid chamber for retractionxe2x80x9d may be provided in above-mentioned gas spring, configured such that by supplying liquid pressure to the liquid chamber for retraction, the pressure-receiving means is made to retract. In this case, even without applying a strong external force to the output piston in opposition to above-mentioned strong urging force, by supplying liquid pressure of a comparatively low pressure to the liquid chamber for retraction, the pressure-receiving means can be easily retracted.
In addition, in the above-mentioned liquid pressure cylinder, a spring device may be provided to put force on the output piston in the retracting direction. In this case, by making the pressure-receiving means retract, the output piston can surely be made to retract due to the force of the spring device.
In addition, it is desirable that above-mentioned liquid chamber for retraction be formed between above-mentioned partitioning means and the pressure-receiving part of the pressure-receiving means. In this case, because the pressure-receiving part of the pressure-receiving means can be made to receive the liquid pressure of the liquid chamber for retraction, the pressure-receiving means can be retracted by supplying hydraulic pressure at a comparatively low pressure to the liquid chamber for retraction.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.